This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The Snf1 kinase is activated by phosphorylation of a conserved threonine residue in its activation loop. Recent studies have found the regulation of this phosphorylation event are controlled by the dephosphorylation reaction. In high glucose, the kinase is readily dephosphorylated and is inactive. In low glucose, the kinase adopts a phosphatase resistance conformation and the phosphorylated, active form accumulates. In this study we will use FRET to test this model by placing YFP and RFP in different positions within the kinase complex. We will use the available strutural data to engineer the YFP and RFP fusions in order to distinguish between the phosphatse accessible form and the phosphatase resistant form of the Snf1 kinase complex.